Ancient reptile footprints are rewriting the history of when animals evolved

Summary

WASHINGTON (AP) — Scientists in Australia have identified the oldest known fossil footprints of a reptile-like animal, dated to around 350 million years ago.The discovery suggests that after the first animals emerged from the ocean around 400 million years ago, they evolved the ability to live exclusively on land much faster than previously assumed. “We had thought the transition from fin to limb took much longer,” said California State University paleontologist Stuart Sumida, who was not involved in the new research. Previously the earliest known reptile footprints, found in Canada, were dated to 318 million years ago. AP AUDIO: How ancient reptile footprints are rewriting the history of when animals evolved to live on land AP correspondent Donna Warder reports on some really old fossil footprints. The ancient footprints from Australia were found on a slab of sandstone recovered near Melbourne and show reptile-like feet with long toes and hooked claws. This image provided by Prof. Per Erik Ahlberg shows a slab of sandstone found near Melbourne, Australia preserving fossil footprints from a reptile-like animal that lived around 350 million years ago. The footprints are highlighted in yellow (front feet) and blue (back feet) and show the movements of three similar animals, researchers say. (Grzegorz Niedzwiedzki/Prof. Per Erik Ahlberg via AP) Scientists estimate the animal was about 2 1/2 feet (80 centimeters) long and may have resembled a modern monitor lizard. The findings were published Wednesday in Nature. The hooked claws are a crucial identification clue, said study co-author and paleontologist Per Ahlberg at Uppsala University in Sweden. “It’s a walking animal,” he said. Only animals that evolved to live solely on land ever developed claws. The earliest vertebrates -- fish and amphibians – never developed hard nails and remained dependent on watery environments to lay eggs and reproduce.But the branch of the evolutionary tree that led to modern reptiles, birds...